1. Field of the Invention
The present invention relates to a nanowire sensor using a nanowire, and more particularly, to a nanowire sensor having a nanowire in a network structure, which uses a nanowire in a network structure including repeated patterns instead of a straight nanowire, thereby obtaining high efficiency and structural stability.
2. Description of the Related Art
An electrochemical sensor is an element which converts a physical or chemical characteristic of a target material into an electrical signal. The electrochemical sensor is expected to be widely used as a biosensor, chemical sensor or environmental sensor, depending on a target material.
In order to sense and analyze a target material using an electrochemical sensor, the electrochemical sensor must have such a high sensitivity that a signal is significantly changed for a fine characteristic of the target material. Furthermore, the electrochemical sensor must have chemical stability for chemical composition of body fluid and physical stability for a flow of fluid. Furthermore, an existing measurement platform must be used to facilitate the use of the electrochemical sensor, and the electrochemical sensor must have a structure which may be easily mass-produced for economic feasibility and practicality.
In this aspect, a silicon sensor fabricated through an existing semiconductor process is the most suitable for requirements of the electrochemical sensor. Among the requirements, a nanowire channel has a one-dimensional structure and an excellent gate control ability, and has a higher ratio of area to volume than a flat panel silicon channel, thereby obtaining a high sensitivity. Thus, much research has been conducted on the nanowire channel.
FIG. 1 is a diagram illustrating a conventional nanowire sensor using a nanowire.
Referring to FIG. 1, the conventional nanowire sensor includes a detection material 40 attached on a gate insulating layer 15 over nanowires formed between a source electrode region S and a drain electrode region D, and performs sensing by changing conductance of a nanowire channel region through charge of a target material 41 which is selectively attached to the detection material. At this time, a separate underwater gate electrode 31 may be provided to fix the potential of a solution.
In the case of the conventional nanowire sensor, the silicon nanowire to which the detection material is fixed may be formed in a bottom-up type or top-down type. The bottom-up type silicon nanowire and the top-down type silicon nanowire have the following problems.
In the case of the bottom-up type nanowire, silicon nanowires formed through a semiconductor process technology such as CVD (Chemical Vapor Deposition) are aligned at specific positions so as to fabricate a sensor. At this time, since the nanowires are not easily synthesized and aligned, there are difficulties in mass-producing the nanowire sensor.
In the case of the top-down type nanowire fabricated through a silicon-on insulator (SOI) substrate, an excellent electric characteristic may be obtained, but there are difficulties in implementing a nanowire having a smaller thickness than the bottom-up type nanowire due to the limit of exposure technology. Furthermore, when a gate-all-around device is implemented to acquire a high sensitivity, nanowires may be bent or collapse in case where the nanowires have a length of several hundred nm or more. Furthermore, the top-down type nanowire is structurally unstable for a flow of fluid.
A general nanowire sensor has a structure in which straight nanowire bundles are connected to a source and drain thereof. At this time, since one target material among arbitrarily-arranged target materials has an influence on only one nanowire, the number of nanowire bundles must be increased to obtain a high sensitivity. Thus, the number of elements with respect to area may be decreased to thereby make it difficult to reduce a cost.